Music, videos, and other media objects are often accompanied by or associated with metadata, or data describing the media objects. Metadata may include information identifying the associated media objects, artists, authors, year of production or publication, genres, etc. Metadata is often displayed by certain media players, such as IPOD and WINDOWS MEDIA PLAYER, to assist users in organizing and recognizing media objects.
For instance, the common MPEG-1 Audio Layer 3 or MP3 format of songs, contains a tag or set of metadata that indicates the song title, track number, artist, album, year of publication, genre, and/or other information describing the MP3. A tag may also include album art comprising such file formats as .jpg and .bmp. The most widespread standard audio tag formats are ID3v1 and ID3v2, and the more recently introduced APEv2. ID3v1 and ID3v2 tags are supported in software such as ITUNES, WINDOWS MEDIA Player, WINAMP, YME, MUSICMATCH and hardware players like APPLE's IPOD, Creative Zen, Toshiba Gigabeat and SONY's WALKMAN. The ID3v2 tag contains up to 256 megabytes of data which can include text-based descriptions of a given song as well as pictures.
Devices and software able to render MP3s are often also able to recognize metadata and display the metdadata. For instance, the song titles, genre descriptions, etc. displayed in the ITUNES and WINDOWS MEDIA Player graphical user interfaces (GUIs) are rendered from metadata embedded in MP3s or retrieved from remote servers. Another metadata format is MPEG-7, a format used to encode data about other media formats, often video formats such as MPEG-1, MPEG-2, MPEG-3, and MPEG-4.